Method and device for transmitting random access and other uplink channels of other cell in mobile communication system carrier aggregation

ABSTRACT

The present invention relates to a transmission of a random access in a specific cell from a plurality of serving cells in a mobile communication system using a carrier aggregation technology, and a method for efficiently transmitting uplink channels other than the random access in another cell. In particular, the method for a terminal to transmit an uplink channel to a base station comprises the steps of: confirming whether an uplink channel for a second carrier having an uplink timing different from a first carrier is included in a subframe transmitting a Random Access Preamble for the first carrier; if included, confirming whether the sum of the electric power required for the transmission of the random access preamble and the electric power required for the transmission of the uplink channel exceeds the maximum transmission electric power of the terminal; and, if exceeding, transmitting the random access preamble preferentially before the uplink channel. In addition, the terminal for transmitting an uplink channel to a base station comprises: a transmitter/receiver for transmitting/receiving a signal to/from the base station; and a control unit for confirming whether the uplink channel for a second carrier having an uplink timing different from a first carrier is included in a subframe for transmitting a random access preamble for the first carrier, and if included, confirming whether the sum of the electric power required for transmitting the Random Access Preamble and the electric power required for transmitting the uplink channel exceeds the maximum transmission electric power of the terminal, and if exceeding, controlling the transmission so that the random access preamble is preferentially transmitted before the uplink channel.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority under 35 U.S.C. §365 toInternational Patent Application No. PCT/KR2012/002585 filed Apr. 5,2012, entitled “METHOD AND DEVICE FOR TRANSMITTING RANDOM ACCESS ANDOTHER UPLINK CHANNELS OF OTHER CELL IN MOBILE COMMUNICATION SYSTEMCARRIER AGGREGATION”. International Patent Application No.PCT/KR2012/002585 claims priority under 35 U.S.C. §365 and/or 35 U.S.C.§119(a) to U.S. Provisional Patent Application No. 61/471,872 filed Apr.5, 2011 and Korean Application No. 10-2012-0035517 filed Apr. 5, 2012,and which are incorporated herein by reference into the presentdisclosure as if fully set forth herein.

TECHNICAL FIELD

The present disclosure relates to a method for a terminal to transmituplink channel to a base station in a wireless communication systemsupporting carrier aggregation. In more particular, the presentdisclosure relates to an uplink channel transmission method andapparatus for transmitting uplink channel when uplink transmissionoccurs in a cell at the same timing when a terminal transmits a randomaccess preamble in a specific cell.

BACKGROUND ART

The mobile communication system has been developed for the user tocommunicate on the move. With the rapid advance of technologies, themobile communication system has evolved to the level capable ofproviding high speed data communication service as well as voicetelephony service. Recently, as one of the next generation mobilecommunication system, Long Term Evolution (LTE) is on thestandardization by the 3^(rd) Generation Partnership Project (3GPP). LTEis a technology designed to provide high speed packet-basedcommunication of up to 100 Mbps and aims at commercial deployment around2010 timeframe.

Meanwhile, unlike voice service, the data service is provided on theresource determined according to the data amount to be transmitted andchannel condition. Accordingly, the wireless communication system,especially cellular communication, is provided with a scheduler managestransmission resource allocation in consideration of the requiredresource amount, channel condition, data amount, etc. This is the factin the LTE system as the next generation mobile communication system,and the scheduler located at the base station manages the transmissionresource allocation.

Recent studies are focused on the LTE-Advanced (LTE-A) for improvingdata rate with the adaptation of several new techniques to legacy LTEsystem. Carrier Aggregation (CA) is one of such technologies. CA is thetechnology that aggregates a plurality of carriers for uplink anddownlink transmission between a User Equipment (UE) and an evolved NodeB (eNB) so as to increases the data reception amount/reception data rateor transmission amount/transmission data rate in proportion to thenumber of aggregated carriers. In LTE, the cell operating on the maincarrier frequency is referred to as Primary Cell (PCell) and the othercells operating on other frequency carriers are referred to as SecondaryCell (SCell).

Meanwhile, with the introduction of repeater and Remote Radio Head(RRH), the positions of antennas responsible for the radiotransmission/reception change (e.g. the transmit/receive antennas forthe secondary carrier may be located at the RRHs while thetransmit/receive antennas for the primary carrier are located at theeNB) and, in this case, it is prefer to acquire the uplink transmissiontiming to a receive antenna near the terminal location rather than theuplink transmission timing to a receive antenna far from the terminallocation.

This means that a plurality of uplink transmission timings may exist andthus there is a need of a method for managing carriers efficiently in acarrier aggregation scenario including a plurality of uplinktransmission timings.

DISCLOSURE OF INVENTION Technical Problem

The present disclosure has been conceived to solve the above problems.The present disclosure aims to provide a method and apparatus fortransmitting uplink channel efficiently, especially when there is theuplink transmission in one cell at the same timing when the UE transmitsthe random access preamble in a specific cell.

Solution to Problem

In accordance with an aspect of the present disclosure, a method for aterminal to transmit uplink channels to a base station in a wirelesscommunication system supporting carrier aggregation of at least onecarrier includes determining whether a subframe carrying a random accesspreamble on a first carrier includes an uplink channel on a secondcarrier having an uplink timing different from the uplink timing of thefirst carrier, determining, when the uplink channel is included, whethera sum of transmit powers required for transmitting the Random AccessPreamble and the uplink channel is greater than a maximum terminaloutput power, and transmitting, when the sum of the required transmitpowers is greater than the maximum terminal output power, the RandomAccess Preamble with priority.

In accordance with another aspect of the present disclosure, a terminalfor transmitting uplink channels to a base station in a wirelesscommunication system supporting carrier aggregation of at least onecarrier includes a transceiver which transmits and receives to and fromthe base station and a control unit which determines whether a subframecarrying a random access preamble on a first carrier includes an uplinkchannel on a second carrier having an uplink timing different from theuplink timing of the first carrier, determines, when the uplink channelis included, whether a sum of transmit powers required for transmittingthe Random Access Preamble and the uplink channel is greater than amaximum terminal output power and controls transmitting, when the sum ofthe required transmit powers is greater than the maximum terminal outputpower, the Random Access Preamble with priority.

Advantageous Effects of Invention

According to the present disclosure, the UE is capable of transmittingthe random access preamble or uplink channel efficiently when an uplinkchannel for a cell is included in the subframe carrying a random accesspreamble for a specific cell

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating network architecture of a 3GPP LTEsystem according to an embodiment of the present disclosure.

FIG. 2 is a diagram illustrating a protocol stack of the LTE system towhich the present invention is applied.

FIG. 3 is a diagram illustrating an exemplary situation of carrieraggregation in the LTE system to which the present invention is applied.

FIG. 4 is a diagram illustrating a principle of uplink timingsynchronization in the OFDM-based 3GPP LTE system to which the presentinvention is applied.

FIG. 5 is a diagram illustrating an exemplary scenario requiring aplurality of uplink timings in carrier aggregation.

FIG. 6 is a diagram illustrating an exemplary case where a random accesschannel of a certain cell and non-random access uplink channels of othercells are transmitted simultaneously.

FIG. 7 is a flowchart illustrating a UE procedure of handling the caseof FIG. 6 according to an embodiment of the present disclosure.

FIG. 8 is a flowchart illustrating a UE procedure of handling the caseof FIG. 6 according to an embodiment of the present disclosure.

FIG. 9 is a block diagram illustrating a configuration of the UEaccording to embodiments of FIGS. 7 and 8.

MODE FOR THE INVENTION

The present disclosure proposes a method for handling a satiation wherethe random access transmission for a specific cell and uplink channelexcluding a random access preamble (e.g. Physical Uplink Shared Channel(PUSCH)) for another cell are transmitted simultaneously.

In an exemplary case where the random access transmission is performedto acquire uplink timing in a specific cell (e.g. cell A), it ispossible for other cells (e.g. cells B and C) have a valid uplink timingdifferent from that of the specific cell to perform uplink transmissionregardless of the random access transmission in the specific cell foracquiring the uplink timing.

In the above example, it is assumed the cells B and C has to have anuplink timing different from that of the cell A performing the randomaccess to acquire uplink timing and have acquired and maintained thevalid uplink timing currently. That is, in the above example, the randomaccess transmission in the specific cell and non-random access uplinkchannels in other cells occur simultaneously.

In the above case, the UE processes the random access transmission withpriority as compared to the non-random access uplink channels in othercells. The reason for processing the random access transmission withpriority as compared to the non-random access uplink channels in othercells is to guarantee the random access transmission, giving up thenon-random access uplink channel transmission, even when the reliabilityof simultaneous transmission of the random access channel and non-randomaccess uplink channel transmissions are not guaranteed (e.g. shortage ofuplink transmit power of the UE) or to transmit the random accesschannel at the original required transmit power and the non-randomaccess uplink channels in other cells at the residual power.

In an another embodiment, the UE may processes the non-random accessuplink channels in other cells with priority as compared to the randomaccess transmission.

In an another embodiment, the UE may processes the uplink transmissionof PCell with priority among the random access channel in one cell andnon-random access uplink channels in other cells. In this case, if therandom access channel is of the PCell, the random access channel istransmitted with priority as compared to the non-random access uplinkchannels in other cells; and otherwise if the random access channel isnot of the PCell (i.e. random access channel of an SCell) and ifnon-random access channel in the PCell is required to be transmittedsimultaneously, the non-random access channel in the PCell istransmitted with priority.

FIG. 1 is a diagram illustrating network architecture of a 3GPP LTEsystem according to an embodiment of the present disclosure. Accordingto an embodiment of the present disclosure, the LTE network includesevolved Node Bs (eNBs) 105, 110, 115, and 120, a Mobility ManagementEntity (MME) 125, and a Serving-Gateway (S-GW) 130. The User Equipment(hereinafter, referred to as UE) 135 connects to an external network viaeNBs 105, 110, 115, and 120 and the S-GW 130. The User Equipment (UE)135 connects to an external network through the eNB 105 and SGW 130. TheeNBs 105, 110, 115, and 120 correspond to the legacy node B of UMTSsystem. The eNB 105 establishes a radio channel with the UE 135 and isresponsible for complex functions as compared to the legacy node B.

In the LTE system, all the user traffic including real time servicessuch as Voice over Internet Protocol (VoIP) are provided through ashared channel and thus there is a need of a device which is located inthe eNB to schedule data based on the state information such as UEbuffer conditions, power headroom state, and channel state. Typically,one eNB controls a plurality of cells. In order to secure the data rateof up to 100 Mbps, the LTE system adopts Orthogonal Frequency DivisionMultiplexing (OFDM) as a radio access technology.

Also, the LTE system adopts Adaptive Modulation and Coding (AMC) todetermine the modulation scheme and channel coding rate in adaptation tothe channel condition of the UE. The S-GW 130 is an entity to providedata bearers so as to establish and release data bearers under thecontrol of the MME 125. MME 125 is responsible for various controlfunctions and connected to a plurality of eNBs 105, 110, 115, and 120.

FIG. 2 is a diagram illustrating a protocol stack of the LTE system towhich the present invention is applied. Referring to FIG. 2, theprotocol stack of the LTE system includes Packet Data ConvergenceProtocol (PDCP) 205 and 240, Radio Link Control (RLC) 210 and 235,Medium Access Control (MAC) 215 and 230, and Physical (PHY) 220 and 225.

The PDCP is responsible for IP header compression/decompression,ciphering, and Integrity Protection. The RRC defines the higher layercontrol information message transmission and related operation/procedurefor handling radio resource. The RLC is responsible for segmenting thePDCP Protocol Data Unit (PDU) into appropriate size.

The MAC is responsible for establishing connection to a plurality of RLCentities so as to multiplex the RLC PDUs into MAC PDUs and demultiplexthe MAC PDUs into RLC PDUs. The PHY performs channel coding on the MACPDU and modulates the MAC PDU into OFDM symbols to transmit over radiochannel or performs demodulating and channel-decoding on the receivedOFDM symbols and delivers the decoded data to the higher layer.

FIG. 3 is a diagram illustrating an exemplary situation of carrieraggregation in the LIE system to which the present invention is applied.Referring to FIG. 3, typically an eNB can use multiple carrierstransmitted and receive in different frequency bands. For example, theeNB 305 can be configured to use the carrier 315 with center frequencyf1 and the carrier 310 with center frequency f3. If carrier aggregationis not supported, the UE 330 has to transmit/receive data unit one ofthe carriers 310 and 315. However, the UE 330 having the carrieraggregation capability can transmit/receive data using both the carriers310 and 315.

The eNB may increase the amount of the resource to be allocated to theUE having the carrier aggregation capability in adaptation to thechannel condition of the UE so as to improve the data rate of the UE.Although the above description has been directed to the transmitter sideof the eNB, it is applicable to the receiver side of the eNB in the samemanner. Unlike the legacy UE transmitting data using one of theplurality carriers, the carrier aggregation-enabled terminal is capableof transmitting data using plural carriers simultaneously so as toincrease the data rate.

In case that a cell is configured with one downlink carrier and oneuplink carrier as a conventional concept, the carrier aggregation can beunderstood as if the UE communicates data via multiple cells. With theuse of carrier aggregation, the peak data rate increases in proportionto the number of aggregated carriers.

In the following description, the phrase “the UE receives data through acertain downlink carrier or transmits data through a certain uplinkcarrier” means to transmit or receive data through control and datachannels provided in a cell corresponding to center frequencies andfrequency bands of the downlink and uplink carriers. Although thedescription is directed to an LTE mobile communication system forexplanation convenience, the present invention can be applied to othertypes of wireless communication systems supporting carrier aggregation.

FIG. 4 is a diagram illustrating a principle of uplink timingsynchronization in the OFDM-based 3GPP LTE system to which the presentinvention is applied. The UE1 is located near the eNB and the UE2 islocated far from the eNB.

T_pro1 indicates the first propagation delay time to the UE1, and T_pro2indicates the second propagation delay to the UE2. The UE1 locates nearthe eNB as compared to the UE2 and thus has a relatively shortpropagation delay (in FIG. 4, T_pro1 is 0.333 us, and T_pro2 is 3.33us).

The initial uplink timing of the UE 1 and UE 2 within a cell of the eNBmismatches the uplink timings of the UEs with the cell found by the eNB.Reference number 401 denotes uplink OFDM symbol transmission timing ofthe UE1, and reference number 403 denotes uplink OFDM symboltransmission timing of the UE2.

By taking notice of the uplink transmission propagation delays of theUE1 and UE2, the eNB may receive the uplink OFDM symbols at the timingsas denoted by reference numbers 407 and 409. The UE1's uplink symbol isreceived by the eNB at the timing 407 with a short propagation delaywhile the UE2's uplink symbol transmitted is received by the eNB at thetiming 409 with relatively long propagation delay.

Reference number 405 denotes a reference reception timing of the eNB.Since the timings 407 and 409 precede the synchronization between theuplink transmission timings of the UE1 and UE2, the uplink OFDM symbolreception and decoding start timing 405 of the eNB, the UE1's uplinkOFDM symbol reception timing 407, and the UE2's uplink OFDM symbolreception timing 409 are different among each other. In this case, theuplink symbols transmitted by the UE1 and UE2 are not orthogonal so asto interfere to each other and, as a consequence, the eNB is likely tofail decoding the uplink symbols transmitted, at the timing 401 and 403,by the UE1 and UE2 due to the interference and the mismatch between theuplink symbol reception timings 407 and 409.

Uplink timing synchronization is a procedure for acquiring the eNB'suplink symbol reception timings with the UE1 and UE2 and, if the uplinktiming synchronization procedure completes, the eNB receives uplink OFDMsymbol to acquire decoding start timing as denoted by reference numbers411, 413, and 415. In the uplink timing synchronization procedure, theeNB transmits Timing Advance (hereinafter, referred to as TA)information to the UEs to notify of the timing adjustment amount.

The TA information may be transmitted in the Random Access Response(RAR) message in response to the random access preamble transmitted bythe UE for initial access or in the Timing Advance Commence MAC ControlElement (TAC MAC CE).

FIG. 5 is a diagram illustrating an exemplary scenario requiring aplurality of uplink timings in carrier aggregation. The Remote RadioHeads (RRHs) 503 operating on frequency band F2 507 are deployed aroundthe macro eNB 501 using frequency band F1 505.

If the UE uses both the macro eNB and RRH (i.e. if the UE near the RRH503 aggregates F1 frequency band and F2 frequency band for uplinktransmission), the downlink/uplink transmission between the UE and theRRH has short propagation delay and the downlink/uplink transmissionbetween the UE and the macro eNB has relatively long propagation delay.This means that the uplink transmission timing to the RRH differs fromthe uplink transmission timing to the macro eNB. There is a need of aplurality of uplink transmission timings in the above carrieraggregation scenario and, in order to acquire initial uplinktransmission timing, it is necessary to configure an uplink transmissiontiming through random access procedure on F2 for the RRH and anotherplink transmission timing through random access procedure on F1 for themacro eNB.

This means that if multiple uplink transmission timings exist in thecarrier aggregation it is necessary to perform the random accessprocedure in multiple cells for synchronizing the uplink transmissiontiming (It is not necessary to perform the random access procedures atthe same timings in the plural cells).

In the present disclosure, the carriers having the same uplink timingsare sorted into a Timing Advance Group (TAG). For example, if one PCelland three SCells A, B, and C are aggregated, the PCell and SCell A havethe same uplink timing, and the SCell B and SCell C have the same uplinktiming, the PCell and SCell A may be grouped into TAG#0 and the SCell Band SCell C into TAB#1.

The TAG#0 including the PCell is referred to as Primary TAG (PTAG) andthe TAG#1 including no PCell is referred to as STAG. PCell is theserving cell operating on the primary carrier to which RRC ConnectionEstablishment has been performed initially or the Handover (HO) targetcell.

FIG. 6 is a diagram illustrating an exemplary case where a random accesschannel of a certain cell and non-random access uplink channels of othercells are transmitted simultaneously. Reference number 601 denotes a UEoperating in carrier aggregation mode and reference number 611 denotesan eNB controlling the serving cells of aggregated carriers.

In FIG. 6, it is assumed that total 4 serving cells (PCell 621, SCell#1723, SCell#2 625, and SCell#3 627) operating on the primary andsecondary carriers are used in the carrier aggregation and the PCell andSCell#1 have the same uplink transmission timing and the SCell#2 andSCell#3 have the same uplink timing (the uplink timing of the PCell andSCell#1 and the uplink timing of the SCell#2 and SCell#3 are differentfrom each other).

If the UE 601 maintains the valid uplink transmission timing for thePCell and SCell#1 but has no valid uplink transmission timinginformation on the SCell#2 and SCell#3 at operation 631, the eNBcommands to UE to perform a random access procedure in the SCell#2 toacquire uplink transmission timing information for the SCell#2 andSCell#3 before starting data transmission through the SCell#2 andSCell#3 at operation 641. The command message may be the PDCCH ordermessage specified in TS36.212 PHY.

If the random access procedure command for the SCell#2 is received, theUE 601 transmits a random access preamble through the SCell#2 using anopen loop power control at operation 661. Since the valid uplinktransmission timing for the PCell and SCell#1 is maintained, there maybe any uplink transmission in the PCell and SCell#1 at the timing oftransmitting the Random Access Preamble through the SCell#2 (configuredaccording to previously received uplink scheduling information orsemi-statically) and, in this case, the non-random access uplink channel(e.g. Physical Uplink Shared Channel (PUSCH)) transmissions 663 and 665may occur in the PCell and SCell#1 at the same time as the Random AccessPreamble transmission 651 in the SCell#2 (in the same subframe).

FIG. 7 is a flowchart illustrating a UE procedure of handling the caseof FIG. 6 according to an embodiment of the present disclosure.

If a random access transmission occurs in a SCell or PCell at operation701, the UE checks whether there is any non-random access Uplink (UL)channel transmission in other cells at the same timing/subframe as therandom access transmission at operation 711. If there is only the randomaccess transmission, the random access transmission is performed asscheduled in the corresponding cell at operation 721.

Otherwise if any non-random access UL channel transmission occurs inother cells, the UE calculates the sum of the transmit powers requiredfor transmitting the random access channel and non-random access uplinkchannel in other cells at operation 731. The transmit power required forrandom access transmission may be calculated using the followingequation.PPRACH=min{P _(CMAX,c)(i),PREAMBLE_RECEIVED_TARGET_POWER+PL_(C)}_[dBm]

P_(PRACH): random access preamble transmission power

P_(CMAX,c)(i): configured UE output power for SCell or PCelltransmitting random access channelPREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep

preambleInitialReceivedTargetPower: value signaled by eNB through RRClayer message for open-loop power control of random access transmission

DELTA_PREAMBLE: power adjustment value determined depending on theformation of random access preamble to be transmitted

PREAMBLE_TRANSMISSION_COUNTER: number of random access preambletransmission times

powerRampingStep: power offset value applied between consecutive randomaccess transmissions (i.e. the power for second random accesstransmission increases as much as powerRanpingStep power offset value ascompared to the first random access transmission)

PL_(C): Pathloss estimation value calculated based on the pathlossreference cell

The sum of the powers required for transmitting non-random access uplinkchannels, i.e. PUSCH transmit powers, in other cells may be calculatedusing the following equation:

PUSCH transmit power calculation example 1 (UE does not transmit PUSCHand PUCCH simultaneously)

${P_{{PUSCH},c}(i)} = {\min\begin{Bmatrix}{{P_{{CMAX},c}(i)},} \\\begin{matrix}{{10{\log_{10}\left( {M_{{PUSCH},c}(i)} \right)}} + {P_{{O\;\_\;{PUSCH}},c}(j)} +} \\{{{\alpha_{c}(j)} \cdot {PL}_{c}} + {\Delta_{{TF},c}(i)} + {f_{c}(i)}}\end{matrix}\end{Bmatrix}}$

PUSCH transmit power calculation example 1 (UE transmits PUSCH and PUCCHsimultaneously)

${P_{{PUSCH},c}(i)} = {\min\begin{Bmatrix}{{10{\log_{10}\left( {{{\hat{P}}_{{CMAX},c}(i)} - {{\hat{P}}_{PUCCH}(i)}} \right)}},} \\\begin{matrix}{{10{\log_{10}\left( {M_{{PUSCH},c}(i)} \right)}} + {P_{{O\;\_\;{PUSCH}},c}(j)} +} \\{{{\alpha_{c}(j)} \cdot {PL}_{c}} + {\Delta_{{TF},c}(i)} + {f_{c}(i)}}\end{matrix}\end{Bmatrix}}$

In the above equations, Pcmax,c (i) denotes the configured UE transmitpower at subframe i in the serving cell c. PLc denotes the pathloss inthe reference cell configured to provide the path loss for use in theserving cell c. The pathloss for used in determining the uplink transmitpower in a certain serving cell may be the pathloss on the downlinkchannel of the corresponding cell or the path loss on the downlinkchannel of a different cell. The eNB notifies the UE of the pathloss tobe used in the call setup procedure.

fc(i) denotes a value of accumulation of the Transmission Power Controlin the serving cell c. PO_PUSCH,C denotes a higher layer parameter asthe sum of cell-specific and UE-specific values. αc denotes a weightapplied to the pathloss in calculating the uplink transmission powerwith 3-bit cell-specific value provided from the higher layer (i.e. thelarger this value is, the more the pathloss influences to the uplinktransmit power).

Although the description is directed to the case where the PUSCH isnon-random access uplink channel transmitted in other cells, thenon-random access uplink channel may be other channels such as PhysicalUplink Control Channel (PUCCH) and Sounding Reference Symbol (SRS).

However, if there is PUCCH and SRS transmission, a different requiredpower calculation formula may be applied. Detailed descriptions on thecalculation of the required transmit power of PUCCH and SRS may beacquired by referencing the 3GPP TS36.213 E-UTRA Physical LayerProcedure.

PUSCH is a physical channel carrying the control information or data ofthe higher layer such as MAC and RRC, PUCCH is a physical channelcarrying PHY layer control information (e.g. Scheduling Request (SR),Channel Quality Information (CQI), and Hybrid ARQ (HARQ) Acknowledgementinformation), and SRS is the physical channel carrying PHY controlinformation for use in uplink channel estimation at the eNB.

The UE checks whether the sum of the powers required for the randomaccess transmission and non-random access uplink channel transmission inother cells which has been calculated at operation 731 is greater thanthe total configured maximum UE output power of the UE at operation 741.The total maximum UE output power of the UE may be converted to a linearvalue for use.

If the sum of the required for transmission is not greater than thetotal maximum UE output power, the UE transmits the random accesschannel and the non-random access uplink channels in other cellssimultaneously at operation 751.

Otherwise if the sum of the required for transmission is greater thanthe total maximum UE output power, the UE processes the random accesstransmission with priority at operation 761. That is, the UE transmitsthe random access channel in the corresponding cell as scheduled.However, the UEs does not transmit (gives up the transmission of) thenon-random access uplink channel occurring simultaneously.

Although FIG. 7 is directed to the case that if it is difficult totransit both the random access channel and the non-random access uplinkchannel in other cell reliably (e.g. due to the uplink transmit powershortage of the UE) the UE processes the random access transmission withpriority as compared to the non-random access uplink channel in othercell, it is also possible to process the non-random access uplinkchannel in other cell with priority as compared to the random accesstransmission.

In this case, the UE processes the non-random access uplink channeltransmission in other cell with priority at operation 761 such that thenon-random access uplink channel transmission in other cell istransmitted as scheduled but the random access transmission is cancelled(abandoned).

In another embodiment, the transmission priority of the random accesschannel and the non-random access uplink channel is determined dependingon which of the random access channel and the non-random access uplinkchannel is transmitted in the PCell.

If the random access channel is of being transmitted in the PCell, theUE processes the random access transmission with priority at operation761 (and gives up non-random access uplink channel transmission) and,otherwise if the non-random access uplink channel is of beingtransmitted in the PCell, the UE processes the non-random access uplinkchannel transmission with priority at operation 761 but cancels (givesup) the random access channel transmission.

FIG. 8 is a flowchart illustrating a UE procedure of handling the caseof FIG. 6 according to an embodiment of the present disclosure.

If a random access transmission occurs in a SCell or PCell at operation801, the UE checks whether there is any non-random access Uplink (UL)channel transmission in other cells at the same timing/subframe as therandom access transmission at operation 811.

If there is only the random access transmission, the random accesstransmission is performed as scheduled in the corresponding cell atoperation 821. Otherwise if any non-random access UL channeltransmission occurs in other cells, the UE calculates the sum of thetransmit powers required for transmitting the random access channel andnon-random access uplink channel in other cells at operation 831. Thetransmit power required for random access transmission may be calculatedusing the following equation.PPRACH=min{P _(CMAX,c)(i),PREAMBLE_RECEIVED_TARGET_POWER+PL_(C)}_[dBm]

P_(PRACH): random access preamble transmission power

P_(CMAX,c)(i): configured UE output power for SCell or PCelltransmitting random access channelPREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep

preambleInitialReceivedTargetPower: value signaled by eNB through RRClayer message for open-loop power control of random access transmission

DELTA_PREAMBLE: power adjustment value determined depending on theformation of random access preamble to be transmitted

PREAMBLE_TRANSMISSION_COUNTER: number of random access preambletransmission times

powerRampingStep: power offset value applied between consecutive randomaccess transmissions (i.e. the power for second random accesstransmission increases as much as powerRanpingStep power offset value ascompared to the first random access transmission)

PL_(C): Pathloss estimation value calculated based on the pathlossreference cell

The sum of the powers required for transmitting non-random access uplinkchannels, i.e. PUSCH transmit powers, in other cells may be calculatedusing the following equation:

PUSCH transmit power calculation example 1 (UE does not transmit PUSCHand PUCCH simultaneously)

${P_{{PUSCH},c}(i)} = {\min\begin{Bmatrix}{{P_{{CMAX},c}(i)},} \\\begin{matrix}{{10{\log_{10}\left( {M_{{PUSCH},c}(i)} \right)}} + {P_{{O\;\_\;{PUSCH}},c}(j)} +} \\{{{\alpha_{c}(j)} \cdot {PL}_{c}} + {\Delta_{{TF},c}(i)} + {f_{c}(i)}}\end{matrix}\end{Bmatrix}}$

PUSCH transmit power calculation example 1 (UE transmits PUSCH and PUCCHsimultaneously)

${P_{{PUSCH},c}(i)} = {\min\begin{Bmatrix}{{10{\log_{10}\left( {{{\hat{P}}_{{CMAX},c}(i)} - {{\hat{P}}_{PUCCH}(i)}} \right)}},} \\\begin{matrix}{{10{\log_{10}\left( {M_{{PUSCH},c}(i)} \right)}} + {P_{{O\;\_\;{PUSCH}},c}(j)} +} \\{{{\alpha_{c}(j)} \cdot {PL}_{c}} + {\Delta_{{TF},c}(i)} + {f_{c}(i)}}\end{matrix}\end{Bmatrix}}$

In the above equations, Pcmax,c (i) denotes the configured UE transmitpower at subframe i in the serving cell c. PLc denotes the pathloss inthe reference cell configured to provide the path loss for use in theserving cell c. The pathloss for used in determining the uplink transmitpower in a certain serving cell may be the pathloss on the downlinkchannel of the corresponding cell or the path loss on the downlinkchannel of a different cell. The eNB notifies the UE of the pathloss tobe used in the call setup procedure.

fc(i) denotes a value of accumulation of the Transmission Power Controlin the serving cell c. PO_PUSCH,C denotes a higher layer parameter asthe sum of cell-specific and UE-specific values. αc denotes a weightapplied to the pathloss in calculating the uplink transmission powerwith 3-bit cell-specific value provided from the higher layer (i.e. thelarger this value is, the more the pathloss influences to the uplinktransmit power).

Although the description is directed to the case where the PUSCH isnon-random access uplink channel transmitted in other cells, thenon-random access uplink channel may be other channels such as PhysicalUplink Control Channel (PUCCH) and Sounding Reference Symbol (SRS).However, if there is PUCCH and SRS transmission, a different requiredpower calculation formula may be applied. Detailed descriptions on thecalculation of the required transmit power of PUCCH and SRS may beacquired by referencing the 3GPP TS36.213 E-UTRA Physical LayerProcedure.

PUSCH is a physical channel carrying the control information or data ofthe higher layer such as MAC and RRC, PUCCH is a physical channelcarrying PHY layer control information (e.g. Scheduling Request (SR),Channel Quality Information (CQI), and Hybrid ARQ (HARQ) Acknowledgementinformation), and SRS is the physical channel carrying PITY controlinformation for use in uplink channel estimation at the eNB.

The UE checks whether the sum of the powers required for the randomaccess transmission and non-random access uplink channel transmission inother cells which has been calculated at operation 831 is greater thanthe total configured maximum UE output power of the UE at operation 841.The total maximum UE output power of the UE may be converted to a linearvalue for use. If the sum of the required for transmission is notgreater than the total maximum UE output power, the UE transmits therandom access channel and the non-random access uplink channels in othercells simultaneously at operation 751.

Otherwise if the sum of the required for transmission is greater thanthe total maximum UE output power, the UE processes the random accesstransmission with priority at operation 861. That is, the UE transmitsthe random access channel in the corresponding cell as scheduled.However, the UEs does not transmit (gives up the transmission of) thenon-random access uplink channel occurring simultaneously.

Although FIG. 8 is directed to the case that if it is difficult totransit both the random access channel and the non-random access uplinkchannel in other cell reliably (e.g. due to the uplink transmit powershortage of the UE) the UE processes the random access transmission withpriority as compared to the non-random access uplink channel in othercell, it is also possible to process the non-random access uplinkchannel in other cell with priority as compared to the random accesstransmission.

In this case, the UE processes the non-random access uplink channeltransmission in other cell with priority at operation 861 such that thenon-random access uplink channel transmission in other cell istransmitted as scheduled but the random access transmission is performedat the residual power remained after allocating the power for use intransmitting the non-random access uplink channel in other cells.

In another embodiment, the transmission priority of the random accesschannel and the non-random access uplink channel is determined dependingon which of the random access channel and the non-random access uplinkchannel is transmitted in the PCell.

If the random access channel is of being transmitted in the PCell, theUE processes the random access transmission with priority at operation861 (transmits the random access channel at the required transmit poweras allocated but the non-random access uplink channel in other cell atthe transmit power available after the power allocation for the randomaccess transmission); and otherwise if the non-random access uplinkchannel is of being transmitted in the PCell, the UE processes thenon-random access uplink channel transmission with priority at operation861 (transmits the non-random access uplink channel in other cell at therequired transmit power as allocated but the random access channel atthe transmit power available after the power allocation for thenon-random access uplink channel in other cells).

FIG. 9 is a block diagram illustrating a configuration of the UEaccording to embodiments of FIGS. 7 and 8.

The UE receives downlink control information/data through a pluralityserving cells established with the eNB by means of the transceiver 901and performs random access transmission and non-random access uplinkchannel transmission in other cells. The transceiver may include atleast one RF channel for a plurality of serving cells.

The power calculating and control unit 921 calculates required powersfor random access and non-random access uplink channel transmission andallocates power for the random access and uplink channel transmissions.

The scheduler drops any of the random access and non-random accessuplink channel transmission selectively according to the priority whenthe sum of the transmit powers required for transmitting the randomaccess and non-random access uplink channels in other cells is greaterthan the total maximum UE output power.

Although preferred embodiments of the invention have been describedusing specific terms, the specification and drawings are to be regardedin an illustrative rather than a restrictive sense in order to helpunderstand the present invention. It is obvious to those skilled in theart that various modifications and changes can be made thereto withoutdeparting from the broader spirit and scope of the invention.

The invention claimed is:
 1. A method for transmitting uplinkinformation by a terminal in a wireless communication system, the methodcomprising: configuring multiple timing advance groups (TAGs) for atleast two serving cells; determining whether a transmission of a randomaccess preamble on a first serving cell belonging to a first TAG and atransmission of an uplink signal on a second serving cell belonging to asecond TAG occur in a same symbol; determining whether a totaltransmission power required for transmitting the random access preambleand the uplink signal exceeds a maximum terminal output power, if thetransmission of the random access preamble and the transmission of theuplink signal occur in the same symbol; and transmitting the randomaccess preamble on the first serving cell, if the total transmissionpower exceeds the maximum terminal output power.
 2. The method of claim1, further comprising dropping the transmission of the uplink on theserving cell.
 3. The method of claim 1, further comprising: adjusting atransmission power of the uplink signal on the second serving cell; andtransmitting the uplink signal on the second serving cell with theadjusted transmission power.
 4. The method of claim 3, wherein thetransmission power of the uplink signal on the second serving cell isadjusted not to exceed the maximum terminal output power.
 5. The methodof claim 2, wherein the transmission of the uplink signal on the secondserving cell is dropped, if the uplink signal on the second serving cellincludes a sounding reference signal (SRS).
 6. The method of claim 3,wherein the transmission power of the uplink signal on the secondserving cell is adjusted, if the uplink signal on the second servingcell includes one of a physical uplink control channel (PUCCH) or aphysical uplink shared channel (PUSCH).
 7. A terminal for transmittinguplink information to a base station in a wireless communication system,the terminal comprising: a transceiver configured to transmit andreceive a signal; and a control unit configured to: configure multipletiming advance groups (TAGs) for at least two serving cells; determinewhether a transmission of a random access preamble on a first servingcell belonging to a first TAG and a transmission of an uplink signal ona second serving cell belonging to a second TAG occur in a same symbol;determine whether a total transmission power required for transmittingthe random access preamble and the uplink signal exceeds a maximumterminal output power, if the transmission of the random access preambleand the transmission of the uplink signal occur in the same symbol; andcontrol the transceiver to transmit the random access preamble on thefirst serving cell, if the total transmission power exceeds the maximumterminal output power.
 8. The terminal of claim 7, wherein the controlunit is configured to drop the transmission of the uplink signal on thesecond serving cell.
 9. The terminal of claim 7, wherein the controlunit is configured to control transmitting the uplink channel withpriority as compared to the random access preamble.
 10. The terminal ofclaim 9, wherein the control unit is configured to adjust a transmissionpower of the uplink signal on the second serving cell and to transmitthe uplink signal on the second serving cell with the adjustedtransmission power.
 11. The terminal of claim 8, wherein thetransmission of the uplink signal on the second serving cell is dropped,if the uplink signal on the different serving cell includes a soundingreference signal (SRS).
 12. The terminal of claim 9, wherein thetransmission power of the uplink signal on the second serving cell isadjusted, if the uplink signal on the second serving cell includes oneof a physical uplink control channel (PUCCH) or a physical uplink sharedchannel (PUSCH).